Palynofacies is a particular sedimentary organic matter, which can reflect sedimentation and lithogenesis environment. In order to evaluate petroleum generating potential of source rock, the palynofacies of lower-middle Jurassic in the east part of northern Qaidam basin have been researched in detail. Based on the identification and statistics of the organic matter, the lower-middle Jurassic may be divided into five palynofacies zones. The first zone distributes in the Xiaomeigou formation, which belongs to assemblage of fusinite and structural terrestrial organic matter.The second zone distributes in the first member of Dameigou formation, which belongs to assemblage of amorphous organic matter. The third zone distributes in the second to fourth members of the Dameigou formation, which belongs to assemblage of fusinite and grass organic matter. The fourth zone distributes in the fifth member of the Dameigou formation, which belongs to assemblage of grass and amorphous organic matter. The fifth zone distributes in the seventh member of the Dameigou formation, which belongs to assemblage of amorphism, semi-amorphism and structural aquatic organic matter. According to the palynofacies analysis, the oil generating potential of these strata has been evaluated. It is indicated that the first and the seventh members of Dameigou formation are the best of oil-generating beds, and the fifth member of Dameigou formation is secondly. The other members is worse.